Slide-valve arrangement for steam-engine cylinders.



No. 746,776. PATENTBD DEG. 15,:-190s.

A. J. BALKWILL.

SLIDE VALVE ARRANGEMENT FORSTEAM ENGINECYLINDERS.

APPLICATION FILED AUG. 28, 1899. H0 MODEL. -5 SHEETd-GIIEBT 1.

No- 746,776. PATENTED DEG. 15,1903.

A. J. BALKWILL; I

SLIDE VALVE ARRANGEMENT FOR STEAMBNGINE CYLINDERS.

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No. 74mm. PATENTBD DEG.15,1903.

A. J. BALKWILL.

. SLIDE VALVE ARRANGEMENT FOR STEAM ENGINE CYLINDERS.

APPLICATION FILED AUG; 8, 99-

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' UNITET) i STATES iatented December 15, 1903.

PATEN T OFFICE.

SLlDE-VALV E-ARRANGEMENT FO'lR STEAM-ENGINE CYLINDERS.

SPECIFICATION forming part Of letters Patent No. 746,776, dated December15, 1903. Application filed August 28, 1899. Serial No. 728,768. (Nomodel.)

To all whom it may conoerm.

Be it known that I, ALFRED J oHN' BALK- WILL, asubject of the Queen ofGreat Britain, residing at 6 Calder Vale road, Wakefield, York, England,have invented certain new and useful Improvements in Slide-ValveArrangements for Steam-Engine Cylinders, of which the following is aspecification.

The object of my invention is an improved slide-valve arrangement forsteam'en gine cylinders whereby with special ports 'and valve part ofthe steam after completing its work at one side of the piston traversesthe valve to the opposite side of the piston, the remainder of the steambeing exhausted. For the purpose of my invention, in addition to theusual steam entry and exhaust ports in the valve-face of the cylinder, Iprovide another or branch port in the valve-face, but leading out fromone of the ordinary ports, this double port having only one port inthe'cylinder.

The slide is formed with an external cham-' her or port outside itsordinary exhaust-port for communication with the additional or auxiliaryport and the ordinary port on the opposite side for the passage of partof the steam from one side of the piston to the other. The Working of myimproved slide-valve arrangement is as follows: The steam pushes thepiston down and at three-fourths stroke the slide-valve shuts the steam0d. Then it expands slightly. Just before the piston gets at the bottomend steam passes round through the top side through the external port ofthe slide-valve to the bottom side of the piston. At a certain point thesteam is shut 0E; but at the very instant it is shut 0d the remainder isexhausted to the atmosphere through the central port, thus allowing thetransferred steam to act expansively in aiding the return of the piston.On the return stroke the whole of the steam which had previously passedthrough the top to the bottom is exhausted. When the steam at the topside of the piston is exhausted, there is only a slight exhaust, but onthe downstroke there is a-full exhaust. Although steam goes in at thetop side, it is nearly all exhausted from the bottom side.

My invention will he clearly understood from the accompanying drawings,in which each figure represents in section an enginecylinder,slide-valve, and valve-casing.

Figure 1 shows the slide-valve in position, with'theinleL-port slightlyopen foradmission of live steam to the top part of the cylinderEOI'VGOIIIIIIGIICGIHBUB of piston-stroke, the exhaust-port being open tobottom of piston. Fig. 2 shows the slide-valve moved for the fulladmission of live steam to the top of the piston, the piston at thistime having reached about one-third of its stroke. Fig. 3 shows thevalve moved over to shut oft the steaminlet, the exhaust being fullyopen from opposite end of cylinder. Fig. 4 shows the piston at the endof its stroke and the ports and supplementary passage in the valve openfor the tranfer of the used steam to opposite end of cylinder. Fig. 5shows the position the valve and piston occupy when thesteamtransference passage is out off and" the exhaust. opened to the toppart of the cylinder.

Ais the cylinder; B, piston CD, cylinderports; E, ordinary exhaust; F,slide-valve; G, slide-valve casing; H,additionalthrough-port inslide-valve F; I, branch port from port D of cylinder A for partialexhaust; J, pistonrod; K, valve-rod; L, steam-supply pipe; M, usualexhaust-passage in slide-valve F.

The action is as follows, assuming the piston B to be at the top of itsstroke, as indi cated in' Fig. 1 Steam enters valve-casing G by the pipeL andpasses through the port 0 for exerting its power against the pistonB until the piston B has traveled to about that portion of itsstrokeindicated in Fig. 3, at which time the valve F will have been moved toclose the port C to the entrance of live steam to the cylinder. The,further expansion otthe steam within the cylinder operates on the pistonto complete the stroke. Asthe piston. is arriving at the end of thestroke the slide-valve is next moved back, as

at Fig. 4:, to bring the supplemental passage H of the slide-valve intocommunication with the ports 0 and D, so that a portion of the usedsteam can pass through the channel thus afforded to the back of thepiston B. Owing to the inertia of the moving parts of the engine thepiston will now be started upon its return stroke. Before it reaches thecenter of the cylinder, however, the valve F will have started towardthe position shown in Fig. 5, gradually moving the passage H out ofcommunication with either of the ports O and D and placing the port 0 incommunication with the exhaust E through port M.

Thus the steam in front of the piston will escape through the exhaust tothe outer air, so that the expansive power of the steam which has beentrapped, so to speak, at the rear of the piston may be utilized inmoving the piston to the end of its return stroke. On the next movementof the slide-valve F, as at Fig. 1, the supplementary or additional portH is closed and the steam at the rear of the piston so used expansivelypasses through port D, branch I, and port M to the exhaustpassage Esimultaneously with the inlet of a fresh charge of steam by the port 0for a new power-stroke of the piston B.

What I claim, and desire to secure by Letters Patent, is-- Incombination with a cylinder, a piston therein, a steam-chest associatedwith the ALFRED JOHN BALKWILL.

Witnesses:

CHARLES HENZELL HOLGATE, CHAS. GILLIAU, Jr.

